After spending 10 minutes searching for the proper plural form of Sasquatch, I grew impatient. Was it Sasquatches? Could I use Bigfeet? Or was it a murder of Sasquatch? Finding little in the way of information on the New York Times site (two instances of Sasquatches) and absolutely nothing in the Chicago Manual of Style, I encountered this cryptid site!

cryptomundo.com

Eureka!

Within cryptozoology, North American hominoid cryptids typically follow the same irregular plural rule as the above animal words, including:

Bigfoot - Bigfoot
Sasquatch - Sasquatch

There are other cryptid names that also follow this pattern, such as:

Mothman - Mothman
Nessie - Nessie

This is definitely a point that Bigfoot should have covered in his excellent book, Me Write Book.